Environmental restrictions have induced many sawmills to seek alternatives to pentachiorophenol (penta) and similar chlorinated phenols for controlling mold and fungal stains on green lumber during storage and shipment. For that purpose, ten alternative stain preventives were evaluated against a traditional penta product (Permatox 101) on studs of Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco], hem-fir [Tsuga heterophylla (Raf.) Sarg.; Abies sp.], and sugar pine [Pinus lambertiana (Dougl.)] in field trials over a 12-month period. Strong solutions of most preventives provided good to excellent protection for 2 months. Efficacy decreased substantially after the studs were stored 6 months through warm weather. Hem-fir, and to a lesser degree, Douglas-fir, were adequately protected for 12 months only by Permatox 101. None of the treatments protected sugar pine for 1 year.